A manufacture method for composite body including a resin molded body formed from a thermoplastic resin composition and a metal body is known which includes the steps of: overlaying the resin molded body formed from the thermoplastic resin composition and the metal body on top of each other; and applying a laser beam from a metal body side so as to weld these bodies together by softening and/or melting at least a part of the resin molded body formed from the thermoplastic resin composition (see Patent Literature 1).